US 12,222,023 B2
Ball screw device and manufacturing method of screw shaft
Ryo Segawa, Fujisawa (JP)
Assigned to NSK LTD., Tokyo (JP)
Appl. No. 18/290,108
Filed by NSK LTD., Tokyo (JP)
PCT Filed Dec. 12, 2022, PCT No. PCT/JP2022/045691
§ 371(c)(1), (2) Date Nov. 9, 2023,
PCT Pub. No. WO2023/132190, PCT Pub. Date Jul. 13, 2023.
Claims priority of application No. 2022-000588 (JP), filed on Jan. 5, 2022.
Prior Publication US 2024/0376969 A1, Nov. 14, 2024
Int. Cl. F16H 25/22 (2006.01); F16H 25/20 (2006.01); F16H 25/24 (2006.01)
CPC F16H 25/2214 (2013.01) [F16H 2025/2087 (2013.01); F16H 2025/2481 (2013.01)] 13 Claims
OG exemplary drawing
 
1. A ball screw device, comprising:
a screw shaft which has a screw portion having a shaft-side ball screw groove having a spiral shape on an outer peripheral surface thereof; and a carrier constituting a planetary speed-reducing mechanism, integrally configured with the screw portion, and arranged on one side in an axial direction of the screw portion, the screw shaft undergoing rotational motion during use,
a nut which has a nut-side ball screw groove having a spiral shape on an inner peripheral surface thereof, and undergoes linear motion during use,
a plurality of balls arranged between the shaft-side ball screw groove and the nut-side ball screw groove, and
a rolling bearing which has an outer ring having an outer ring raceway on an inner peripheral surface thereof, an inner ring raceway provided on a portion facing the outer ring raceway in a radial direction, and a plurality of rolling bodies arranged between the outer ring raceway and the inner ring raceway so as to be able to roll freely, and supports the carrier so as to be able to rotate freely, wherein
the inner ring raceway is directly formed on an outer peripheral surface of the carrier, the screw portion has an incomplete screw portion at an end portion on the one side in the axial direction on the outer peripheral surface, and
a distance from an end portion on the one side in the axial direction of the nut-side ball screw groove to a side surface on the one side in the axial direction of the nut is greater than a distance from a boundary between the incomplete screw portion and the shaft-side ball screw groove to a side surface on the other side in the axial direction of the carrier.